1. Field of the Invention
The present invention relates to a rotor of a rotating electric machine, particularly relates to a constitution for reducing wind sound by a flow of air at inside of a rotor core in a rotor structure of a vehicular alternating current generator or a vehicular alternating current generator motor.
2. Description of the Related Art
A core of a rotor of a rotating electric machine according to a related art includes a field winding and a cylindrical portion wound with the field winding via an insulating member, a yoke portion widened from the cylindrical portion in an outer peripheral direction, and a plurality of claw-like magnetic poles extended in an axial direction from an outer periphery of the yoke portion to surround to incorporate the field coil and fold to bend to be brought in mesh with each other alternately. As described above, the claw-like magnetic pole portion is constituted by a cantilever shape and a certain constant clearance between the magnetic poles is provided between contiguous ones of the claw-like magnetic poles such that a magnetic flux is prevented from being leaked between the two claws.
According to the rotating electric machine having above-described Lundell type rotor, the magnetic flux is generated by making current flow at the field winding, by a change in the magnetic flux generated in accordance with rotation of the rotor, alternating current is made to flow at an armature winding to provide a power generating function.
Further, in recent years, there is also a rotor constituted by arranging a magnet between the claw-like magnetic poles for increasing an output (refer to, for example, Patent Reference 1).
[Patent Reference 1] JP-A-9-163700
According to the related art, there is a space between the field winding wound around the cylindrical portion of the core and an inner peripheral face of the claw-like magnetic pole as well as between the claw-like magnetic poles, in rotating the rotor, wind sound is emitted by draft both from a front side and a rear side, particularly, a component thereof in a peripheral direction produced between the inner periphery of the claw-like magnetic pole and an outer peripheral face of the field winding to cause noise of vehicular alternating current generator. Particularly, since draft paths by a number of magnetic poles multiplied by an integer are formed, noise having a component of a number of an order of the number of magnetic poles multiplied by an integer is emitted to pose a problem of noise.
Further, in recent years, although there is a case of applying a magnet between the claw-like magnetic poles in order to increase power, even in such a case, there are spaces among the field winding wound around the cylindrical portion of the core and inner peripheral faces of the claw-like magnetic poles and an inner peripheral face of the magnet, faces of the field windings opposed thereto are constituted by recesses and projections by the magnet and therefore, wind sound is similarly emitted by draft both from the front side and the rear side to cause the noise of the vehicular alternating current generator.